Some very nice broken IPv6 networks at Google and Akamai

Andras Toth diosbejgli at
Tue Nov 11 19:09:18 CET 2014

On Tue, Nov 11, 2014 at 3:36 PM, Jeroen Massar <jeroen at> wrote:

> If you expect that they have outages that they cannot quickly see or
> not, then you should also expect a blacklist like to be broken or not
> properly update. Hence, better to see the problems and to alert the
> folks so that they can fix these issues properly (though Google is now
> just hacking around with MSS clamping...).


Google has been doing MSS clamping for a long time, I've seen this myself
in packet captures and Lorenzo also confirmed in his email:
"...some Google servers temporarily stopped doing MSS clamping."

They do it for a good reason: to prevent PMTUD as it introduces delay and
their customers (eyeballs) wouldn't like it. Lorenzo and others explained
this too several times.

The world is not spinning around sixxs and your design ideas. Please turn
off write-only.


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